1. Field of the Invention
This invention relates to a sheet processing apparatus for fetching sequentially sheets on which images are formed by an image forming apparatus such as, e.g., photocopiers, printers, and so on, stapling the plural sheets with a stapling means, and folding the sheets in folio and an image forming apparatus.
2. Description of Related Art
Today some image forming apparatus such as photocopiers or the like can do bookbinding by stapling plural sheets and folding the sheets in folio where connected with a sheet processing apparatus. Such a sheet processing apparatus capable of bookbinding fetches sequentially the sheets on which images are formed at the image forming apparatus body, staples the sheets at about the center of the sheet bundle upon driving the stapler unit, and folds the sheets in folio where the sheets are conveyed to a folding means.
As a structure for folding the sheets in folio, it is structured by a folding roller means made of a roller pair, and a projecting means made of a projecting plate and so on. The projecting plate fold the sheet bundle upon projecting the stapled position of the sheet bundle between the nip portions, and the folded sheet bundle is pressed and conveyed by the roller pair to fold the bundle in folio. Therefore, the sheet bundles delivered to the delivery tray are delivered in a state that the sheet bundles are folded in folio and bound in a book form at the center stapled position of the sheets.
The staple operation is done by driving a forming portion to an anvil opposing with respect to the sheet path, and at that time, a staple fastening the sheet bundle may remain as fitted in a groove on the anvil. If the sheet bundle is conveyed as it is, the staple may be trapped to cause conveyance failures.
This invention is made with respect to the above viewpoint, and it is an object to provide a sheet processing apparatus and an image forming apparatus using this to prevent occurrence of conveyance failures in which after the staple operation the staple is trapped in the groove on the anvil.